Question 1

For the reaction shown below the equilibrium constant expression for Kc = ________.
HF(aq)+ H2O(l)⇌ H3O+(aq)+ F-(aq)

Accepted Answer

Question 2

Which one of the following statements about the equilibrium constant,Kp,is false?

Accepted Answer

A) Δn is equal to the sum of the coefficients of the gaseous products minus the sum of the coefficients of the gaseous reactants. 
B) The relationship between Kp and Kc is: Kp = Kc (RT)Δn 
C) The units for Kp are usually omitted. 
D) Total pressures are used in the equilibrium equation in place of molar concentrations. 
A) Δn is equal to the sum of the coefficients of the gaseous products minus the sum of the coefficients of the gaseous reactants. 
B) The relationship between Kp and Kc is: Kp = Kc (RT)Δn 
C) The units for Kp are usually omitted. 
D) Total pressures are used in the equilibrium equation in place of molar concentrations. D

Question 3

The dissolution of calcium hydroxide is exothermic: Ca(OH)2(s)⇌ Ca2+(aq)+ 2 OH-(aq)
What happens when the solution of Ca(OH)2 is heated?

Accepted Answer

A) The amount of Ca(OH)2(s)decreases. 
B) The amount of Ca(OH)2(s)increases. 
C) The amount of Ca(OH)2(s)remains unchanged. 
D) The Ca(OH)2(s)completely dissolves. 
A) The amount of Ca(OH)2(s)decreases. 
B) The amount of Ca(OH)2(s)increases. 
C) The amount of Ca(OH)2(s)remains unchanged. 
D) The Ca(OH)2(s)completely dissolves. B

Question 4

When baking soda is heated it decomposes according to the following reaction: 2 NaHCO3(s)⇌ Na2CO3(s)+ H2O(g)+ CO2(g)
If sufficient baking soda is placed in a container and heated to 90°C,the total pressure of the gases is 0.5451 atm.What is the value of Kp at that temperature?

Accepted Answer

A) 0.07428 
B) 0.2973 
C) 0.4228 
D) 1.091 
A) 0.07428 
B) 0.2973 
C) 0.4228 
D) 1.091

Question 5

Which change in the system will drive equilibrium to the left in the reaction below? N2O5(g)⇌ NO2(g)+ NO3(g)

Accepted Answer

A) decrease the amount of NO3 
B) increase the amount of N2O5 
C) decrease the volume 
D) increase the volume 
A) decrease the amount of NO3 
B) increase the amount of N2O5 
C) decrease the volume 
D) increase the volume

Question 6

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation: PCl5(g)⇌ PCl3(g)+ Cl2(g)
At 250° 0.250 M PCl5 is added to the flask.If Kc = 1.80,what are the equilibrium concentrations of each gas?

Accepted Answer

A) [PCl5] = 0.0280 M,[PCl3] = 0.222 M,and [Cl2] = 0.222 M 
B) [PCl5] = 0.125 M,[PCl3] = 0.474 M,and [Cl2] = 0.474 M 
C) [PCl5] = 1.80 M,[PCl3] = 1.80 M,and [Cl2] = 1.80 M 
D) [PCl5] = 2.27 M,[PCl3] = 2.02 M,and [Cl2] = 2.02 M 
A) [PCl5] = 0.0280 M,[PCl3] = 0.222 M,and [Cl2] = 0.222 M 
B) [PCl5] = 0.125 M,[PCl3] = 0.474 M,and [Cl2] = 0.474 M 
C) [PCl5] = 1.80 M,[PCl3] = 1.80 M,and [Cl2] = 1.80 M 
D) [PCl5] = 2.27 M,[PCl3] = 2.02 M,and [Cl2] = 2.02 M

Question 7

Kp is equal to 48.70 at 731 K for the reaction: H2(g)+ I2(g)⇌ 2 HI(g).Initially the mixture contains 0.08592 atm each of H2 and I2 and 1.0000 atm of HI.What is the pressure of HI at equilibrium?

Accepted Answer

A) 0.7955 atm 
B) 0.9108 atm 
C) 0.9140 atm 
D) 0.9498 atm 
A) 0.7955 atm 
B) 0.9108 atm 
C) 0.9140 atm 
D) 0.9498 atm

Question 8

At 298 K,Kc = 1.7 × 10-56 for the reaction 3 O2(g)⇌ 2 O3(g).What is the value of Kp at this temperature?

Accepted Answer

Question 9

Which of the following changes in reaction conditions will not alter the composition of a homogeneous equilibrium mixture of gases in a reaction having unequal moles of gaseous products and reactants?

Accepted Answer

A) addition of a catalyst 
B) addition of reactants 
C) decreasing the temperature 
D) increasing the volume 
A) addition of a catalyst 
B) addition of reactants 
C) decreasing the temperature 
D) increasing the volume

Question 10

The enthalpy for the following reaction is 136 kJ.If the reaction takes place in a closed container,which one of the following reaction conditions will not decrease the concentration of water vapor? 2 NaHCO3(s)⇌ Na2CO3(s)+ CO2(g)+ H2O(g)

Accepted Answer

A) remove CO2 
B) cool the container 
C) decrease the volume of the container 
D) add some NaHCO3 
A) remove CO2 
B) cool the container 
C) decrease the volume of the container 
D) add some NaHCO3

Question 11

If additional SCN- is added to the equilibrium system shown below,Le Châtelier's principle predicts a net reaction from ________ to ________,causing the red color to become ________.
Fe3+(aq)+ SCN-(aq)⇌ FeSCN2+(aq)
yellow colorless red

Accepted Answer

Question 12

For the reaction shown below the value of Kp is ________ than the value of Kc,because Δn = ________.
N2O4(g)⇌ 2 NO2(g)

Accepted Answer

Question 13

The following pictures represent mixtures of A2B4 molecules and AB2 molecules,which interconvert according to the equation A2B4 ⇌ 2 AB2.If mixture (1)is at equilibrium,which of the other mixtures are also at equilibrium?

Accepted Answer

A) mixture (2) 
B) mixture (3) 
C) mixture (4) 
D) None of the other mixtures are at equilibrium. 
A) mixture (2) 
B) mixture (3) 
C) mixture (4) 
D) None of the other mixtures are at equilibrium.

Question 14

Write the equilibrium equation for the reverse reaction: 2 CH4(g)+ 3 O2(g)⇌ 2 CO(g)+ 4 H2O(g)

Accepted Answer

A) Kp' =   
B) Kp' =   
C) Kp' =   
D) Kp' =   
A) Kp' =   
B) Kp' =   
C) Kp' =   
D) Kp' =

Question 15

The following pictures represent the equilibrium state for four different reactions of the type   A atoms are unshaded.X atoms are shaded.  
-Which reaction has the largest equilibrium constant?

Accepted Answer

A) A2 + B2 ⇌ 2 AB 
B) A2 + C2 ⇌ 2 AC 
C) A2 + D2 ⇌ 2 AD 
D) A2 + E2 ⇌ 2 AE 
A) A2 + B2 ⇌ 2 AB 
B) A2 + C2 ⇌ 2 AC 
C) A2 + D2 ⇌ 2 AD 
D) A2 + E2 ⇌ 2 AE

Question 16

Which statement about the equilibrium constant is true? The value of Kc

Accepted Answer

A) changes as product concentration changes. 
B) changes as reactant concentration changes. 
C) changes as temperature changes. 
D) changes under the conditions described in A-C. 
A) changes as product concentration changes. 
B) changes as reactant concentration changes. 
C) changes as temperature changes. 
D) changes under the conditions described in A-C.

Question 17

According to Le Châtelier's principle,if the volume of the vessel containing the equilibrium system shown below is decreased,there will be an increase in the concentration of ________ and a decrease in the concentration of ________.
H2(g)⇌ 2 H(g)

Accepted Answer

Question 18

Which of the following is the correct equilibrium constant expression for this reaction? (Hint: check the reaction coefficients) Fe(s)+ O2(g)⇌ Fe2O3(s)

Accepted Answer

A) K =   
B) K =   
C) K =   
D) K =   
E) K = [O2}3 
A) K =   
B) K =   
C) K =   
D) K =   
E) K = [O2}3

Question 19

Consider the interconversion of A molecules (shaded spheres)and B molecules (unshaded spheres)according to the reaction A ⇌ B.Each of the following series of pictures represents a separate experiment in which time increases from left to right.  
-Which of these experiments has resulted in an equilibrium state?

Accepted Answer

A) all of the experiments except experiment (1) 
B) all of the experiments except experiment (2) 
C) all of the experiments except experiment (3) 
D) all of the experiments except experiment (4) 
A) all of the experiments except experiment (1) 
B) all of the experiments except experiment (2) 
C) all of the experiments except experiment (3) 
D) all of the experiments except experiment (4)

Question 20

The esterification of acetic acid and ethanol is given by the reaction below: C2H5OH(aq)+ CH3COOH(aq)⇌ CH3COOC2H5(aq)+ H2O(l)
When 1.00 mol of ethanol was mixed with 2.00 mol of acid in a 1.00 L flask,0.86 mol of ester was formed at room temperature.What is the value of the equilibrium constant,Kc?

Accepted Answer

A) 0.43 
B) 2.3 
C) 4.6 
D) 5.4 
A) 0.43 
B) 2.3 
C) 4.6 
D) 5.4

Exam 14: Chemical Equilibrium

For the reaction shown below the equilibrium constant expression for Kc = ________. HF(aq)+ H2O(l)⇌ H3O+(aq)+ F-(aq)

Which one of the following statements about the equilibrium constant,Kp,is false?

The dissolution of calcium hydroxide is exothermic: Ca(OH)2(s)⇌ Ca2+(aq)+ 2 OH-(aq) What happens when the solution of Ca(OH)2 is heated?

When baking soda is heated it decomposes according to the following reaction: 2 NaHCO3(s)⇌ Na2CO3(s)+ H2O(g)+ CO2(g) If sufficient baking soda is placed in a container and heated to 90°C,the total pressure of the gases is 0.5451 atm.What is the value of Kp at that temperature?

Which change in the system will drive equilibrium to the left in the reaction below? N2O5(g)⇌ NO2(g)+ NO3(g)

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation: PCl5(g)⇌ PCl3(g)+ Cl2(g) At 250° 0.250 M PCl5 is added to the flask.If Kc = 1.80,what are the equilibrium concentrations of each gas?

Kp is equal to 48.70 at 731 K for the reaction: H2(g)+ I2(g)⇌ 2 HI(g).Initially the mixture contains 0.08592 atm each of H2 and I2 and 1.0000 atm of HI.What is the pressure of HI at equilibrium?

At 298 K,Kc = 1.7 × 10-56 for the reaction 3 O2(g)⇌ 2 O3(g).What is the value of Kp at this temperature?

Which of the following changes in reaction conditions will not alter the composition of a homogeneous equilibrium mixture of gases in a reaction having unequal moles of gaseous products and reactants?

The enthalpy for the following reaction is 136 kJ.If the reaction takes place in a closed container,which one of the following reaction conditions will not decrease the concentration of water vapor? 2 NaHCO3(s)⇌ Na2CO3(s)+ CO2(g)+ H2O(g)

If additional SCN- is added to the equilibrium system shown below,Le Châtelier's principle predicts a net reaction from ________ to ________,causing the red color to become ________. Fe3+(aq)+ SCN-(aq)⇌ FeSCN2+(aq) yellow colorless red

For the reaction shown below the value of Kp is ________ than the value of Kc,because Δn = ________. N2O4(g)⇌ 2 NO2(g)

The following pictures represent mixtures of A2B4 molecules and AB2 molecules,which interconvert according to the equation A2B4 ⇌ 2 AB2.If mixture (1)is at equilibrium,which of the other mixtures are also at equilibrium?

Write the equilibrium equation for the reverse reaction: 2 CH4(g)+ 3 O2(g)⇌ 2 CO(g)+ 4 H2O(g)

The following pictures represent the equilibrium state for four different reactions of the type A atoms are unshaded.X atoms are shaded. -Which reaction has the largest equilibrium constant?

Which statement about the equilibrium constant is true? The value of Kc

According to Le Châtelier's principle,if the volume of the vessel containing the equilibrium system shown below is decreased,there will be an increase in the concentration of ________ and a decrease in the concentration of ________. H2(g)⇌ 2 H(g)

Which of the following is the correct equilibrium constant expression for this reaction? (Hint: check the reaction coefficients) Fe(s)+ O2(g)⇌ Fe2O3(s)

Chemical Tools: Experimentation and Measurement

Atoms, molecules, and Ions

Mass Relationships in Chemical Reactions

Reactions in Aqueous Solutions

Periodicity and the Electronic Structure of Atoms

Ionic Compounds: Periodic Trends and Bonding

Covalent Bonding and Electron-Dot Structures

Covalent Compounds: Bonding Theories and Molecular Structure

Thermochemistry: Chemical Energy

Gases: Their Properties and Behavior

Liquids, solids, and Phase Changes

Solutions and Their Properties

Chemical Kinetics

Aqueous Equilibria: Acids and Bases

Applications of Aqueous Equilibria

Thermodynamics: Entropy, free Energy, and Equilibrium

Electrochemistry

Nuclear Chemistry

Transition Elements and Coordination Chemistry

Metals and Solid-State Materials

The Main-Group Elements

Connections to Organic and Biological Chemistry

Filters

For the reaction shown below the equilibrium constant expression for K_c= ________. HF(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ F^-(aq)

Which one of the following statements about the equilibrium constant,K_p,is false?

The dissolution of calcium hydroxide is exothermic: Ca(OH)₂(s)⇌ Ca²⁺(aq)+ 2 OH^-(aq) What happens when the solution of Ca(OH)₂ is heated?

When baking soda is heated it decomposes according to the following reaction: 2 NaHCO₃(s)⇌ Na₂CO₃(s)+ H₂O(g)+ CO₂(g) If sufficient baking soda is placed in a container and heated to 90°C,the total pressure of the gases is 0.5451 atm.What is the value of K_p at that temperature?

Which change in the system will drive equilibrium to the left in the reaction below? N₂O₅(g)⇌ NO₂(g)+ NO₃(g)

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation: PCl₅(g)⇌ PCl₃(g)+ Cl₂(g) At 250° 0.250 M PCl₅ is added to the flask.If K_c = 1.80,what are the equilibrium concentrations of each gas?

K_p is equal to 48.70 at 731 K for the reaction: H₂(g)+ I₂(g)⇌ 2 HI(g).Initially the mixture contains 0.08592 atm each of H₂ and I₂ and 1.0000 atm of HI.What is the pressure of HI at equilibrium?

At 298 K,K_c = 1.7 × 10^-56 for the reaction 3 O₂(g)⇌ 2 O₃(g).What is the value of K_p at this temperature?

The enthalpy for the following reaction is 136 kJ.If the reaction takes place in a closed container,which one of the following reaction conditions will not decrease the concentration of water vapor? 2 NaHCO₃(s)⇌ Na₂CO₃(s)+ CO₂(g)+ H₂O(g)

If additional SCN^- is added to the equilibrium system shown below,Le Châtelier's principle predicts a net reaction from to ,causing the red color to become . Fe³⁺(aq)+ SCN^-(aq)⇌ FeSCN²⁺(aq) yellow colorless red

For the reaction shown below the value of K_p is ________ than the value of K_c,because Δn = ________. N₂O₄(g)⇌ 2 NO₂(g)

The following pictures represent mixtures of A₂B₄ molecules and AB₂ molecules,which interconvert according to the equation A₂B₄ ⇌ 2 AB₂.If mixture (1)is at equilibrium,which of the other mixtures are also at equilibrium?

Write the equilibrium equation for the reverse reaction: 2 CH₄(g)+ 3 O₂(g)⇌ 2 CO(g)+ 4 H₂O(g)

Which statement about the equilibrium constant is true? The value of K_c

According to Le Châtelier's principle,if the volume of the vessel containing the equilibrium system shown below is decreased,there will be an increase in the concentration of and a decrease in the concentration of . H₂(g)⇌ 2 H(g)

Which of the following is the correct equilibrium constant expression for this reaction? (Hint: check the reaction coefficients) Fe(s)+ O₂(g)⇌ Fe₂O₃(s)